Answer:
a. pH = 4.56
b. Change in pH = 0.85
c. Change in pH = 5.4
Explanation:
a. The pKa of lactic buffer is: 3.86.
Using Henderson-Hasselbalch formula for the lactic buffer:
pH = 3.86 + log [Lactate] / [Lactic acid]
Where [] is molarity of each compound but could be taken as moles
Replacing:
pH = 3.86 + log [0.050 moles] / [0.010 moles]
pH = 4.56
b. The HCl added reacts with Lactate producing lactic acid. Moles of HCl are:
5x10⁻³L * (0.5mol /L) = 0.025 moles HCl
Moles of lactate: 0.050moles - 0.025 moles = 0.025 moles
Moles lactic acid: 0.010 moles + 0.025 moles = 0.035 moles
pH = 3.86 + log [0.025 moles] / [0.035 moles]
pH = 3.71
Change in pH = 4.56 - 3.71 = 0.85
c. 1L of pure water has a pH of 7. 0.025 moles of HCl = 0.025 moles H⁺ in 1.005L:
0.025 mol / 1.005L = 0.0249M = [H⁺]
As pH = -log [H⁺]
pH = 1.6
Change in pH = 7.0 - 1.6 = 5.4
Archimedes tells us the lifting power of a balloon (how much mass it can lift) is equal to the difference between the mass of the balloon and the mass of the air it displaces. That is, if the balloon occupies the same volume as 10 kg of air, but the balloon only weighs 2 kg, then the balloon can lift 8 kg. gas densityH2 0.09 kg/m3He 0.18 kg/m3Air 1.23 kg/m3 Airships have sometimes been filled with hydrogen (H), but hydrogen is very flammable, and after the Hindenburg caught fire and crashed in 1937 with serious loss of life airships have nearly always been filled with helium (He) instead. Suppose a new airship Star of Balogna will have the shape of a cylinder 40. m long, with a radius of 4.0 m, and will weigh 750. kg without any gas inside it. Suppose also the average passenger weighs 80 kg. Calculate how many passengers the Balogna could carry if it were filled with hydrogen, and also if it were filled with helium. Passengers with Hz: 29Passengers with He: 26
Answer:
the Balogna could carry 19 passengers if filled with Hydrogen.
the Balogna could carry 17 passengers if filled with Helium.
Explanation:
Given that:
the radius of the cylinder r = 4.0 cm
the height h = 40 m
the volume of the cylinder will be:
[tex]V = \pi r^2 h[/tex]
V = π (4.0 m)² (40)
V = 2010.62 m³.
where the density of the air = 1.23 kg/m³
the mass of the displaced air = Volume V ×density of the air
= 2010.62 m³ × 1.23 kg/m³
= 2473.0626 kg
To calculate how many passengers the Balogna could carry if it were filled with hydrogen, we have the following:
We are given the density of H₂ to be = 0.090 kg/m³
Therefore, the mass of Helium in the balloon = Volume V × density of the hydrogen
= 2010.62 m³ × 0.090 kg/m³
= 180.9558 kg
The total mass of the balloon = mass of H₂ + mass of empty balloon.
The total mass of the balloon = (180.9558+ 750) kg
= 930.9558 kg
Now, the Mass difference = mass of the air displaced -total mass of the balloon.
the Mass difference = (2473.0626 - 930.9558 ) kg
the Mass difference = 1542.1068 kg
∴
number of persons = mass difference/ mass of passenger
the number of persons = 1542.1068 kg /80 (kg/person)
the number of persons = 19.27 persons
the number of passengers [tex]\simeq[/tex] 19 passengers.
To calculate how many passengers the Balogna could carry if it were filled with helium, we have the following:
We are given the density of Helium to be = 0.18 kg/m³
Therefore, the mass of Helium in the balloon = Volume V × density of the hydrogen
= 2010.62 m³ × 0.18 kg/m³
= 361.9116 kg
The total mass of the balloon = mass of Helium + mass of empty balloon.
The total mass of the balloon = (361.9116 + 750) kg
= 1111.9116 kg
Now, the Mass difference = mass of the air displaced -total mass of the balloon.
the Mass difference = (2473.0626 - 1111.9116 ) kg
the Mass difference = 1361.151 kg
∴
number of persons = mass difference/ mass of passenger
the number of persons = 1361.151 kg /80 (kg/person)
the number of persons = 17.01 persons
the number of passengers [tex]\simeq[/tex] 17 passengers.
Lead has a density of 11.34 g/mL, if you weigh an empty beaker and it weighs 245.61 grams, then add lead until the scale reads 350.52 grams, what is the volume of lead that you have? *
Answer:
Explanation:
wt. of the lead = wt. of ( flask + lead) - wt.of the empty flask
350.52- 245.61= 104.91 grams of lead
density = mass/volume
11.43= 104.91/V
V = 9.178 ml
A compound contains 16.7 g of iridium and 10.3 g of selenium, what is its empirical formula?
Answer:
THE EMPIRICAL FORMULA OF THE COMPOUND IS Ir Se2
Explanation:
Iridium = 16.7 g
Selenium = 10.3 g
Total mass = 16.7 + 10.3 = 27 g
To calculate the empirical formula, we first calculate the percentage com[position of the individual elements.
Percentage composition of iridium = 16.7 / 27 * 100 = 61.85 %
Percentage composition of selenium = 10.3 / 27 * 100 = 38.15 %
Next is to divide the percentage composition of each element by their respective molecular masses
Molecular mass of iridium = 192 g/mol
Molecular mass of selenium = 79g/mol
Iridium = 61.85 / 192 = 0.3221
Selenium = 38.15 / 79 = 0.4829
Next is to divide the values by the smaller of the two values
Iridium = 0.3221 / 0.3221 = 1
Selenium = 0.4829 / 0.3221 = 1.5
Next is to round up the values to a whole number
Iridium = 1
Selenium = 2
The empirical formula therefore is Ir Se2
Though alchemists were often superstitious, they left a rich legacy for modern chemists. What was their main contribution?
though alchemists were often superstitious, they left a rich legacy of modern chemists. what was their main contribution-
Explanation:
they were the first to preform experiments.
Select the correct answer.
Which phrase best describes heat?
O A. the energy that an object has as a result of its temperature
OB. the average translational kinetic energy of the particles in an object
ОС. the energy transferred between objects at different temperatures
OD
the total amount of energy possessed by the particles in an object
Answer:
C is the answer hope I helped you have a good day by
Which is not true about the liquid state of matter?
The liquid state has a definite volume and a definite shape.
The liquid state takes on the shape of its container.
The liquid state has a definite volume and an indefinite shape.
The particles in a liquid can easily move past each other.
Answer:
The liquid state has a definite volume and a definite shape.
SN1 reactions of the type, Nu- + RL → Nu–R + L-, are favoured:a. when tertiary substrates are used. b. by using a high concentration of the nucleophile. c. when L- is a strong base. d. by use of an aprotic solvent.
A children’s pain relief elixir contains 10.6 cg acetaminophen per 1 teaspoon. The dosage recommended for a child who weighs 34 lbs, is 1.5 teaspoons. What is the dosage of acetaminophen, expressed as mg acetaminophen/kg body weight, for a child weighing 34 lbs?(1 kg=2.205 lbs)
Answer:
Dosage of acetaminophen = 15.9 cg acetaminophen
Explanation:
Given:
1 teaspoon = 10.6 cg acetaminophen
Dosage to 34 lbs child = 34 lbs
Given dose = 1.5 teaspoon
Find:
Dosage of acetaminophen
Computation:
⇒ Dosage of acetaminophen = 1.5 teaspoon × [10.6 cg acetaminophen]
Dosage of acetaminophen = 15.9 cg acetaminophen
help pls with chemistry question
Answer:
1×10⁸ Hz.
Explanation:
From the question given above, the following data were obtained:
Wavelength (λ) = 3 m
Frequency (f) =?
The wavelength of a wave and it's frequency are related by the following equation:
Velocity (v) = wavelength (λ) × frequency (f)
v = λf
With the above equation, we can obtain the frequency of the light wave as follow:
Wavelength (λ) = 3 m
Velocity (v) of light = 3×10⁸ m/s
Frequency (f) =?
v = λf
3×10⁸ = 3 × f
Divide both side by 3
f = 3×10⁸ / 3
f = 1×10⁸ Hz
Therefore, the frequency of the light wave is 1×10⁸ Hz
How many grams of chlorine gas are present in a 150. liter cylinder of chlorine held at a pressure of 1.00 atm and 0. °C? Group of answer choices
Answer:
474 grams of chlorine gas are present in a 150 liter cylinder of chlorine held at a pressure of 1.00 atm and 0 °C
Explanation:
An ideal gas is a theoretical gas that is considered to be composed of randomly moving point particles that do not interact with each other. Gases in general are ideal when they are at high temperatures and low pressures.
The pressure, P, the temperature, T, and the volume, V, of an ideal gas, are related by a simple formula called the ideal gas law:
P*V = n*R*T
where P is the gas pressure, V is the volume that occupies, T is its temperature, R is the ideal gas constant, and n is the number of moles of the gas.
In this case:
P= 1.00 atmV= 150 Ln= ?R= 0.082 [tex]\frac{atm*L}{mol*K}[/tex]T= 0 C= 273 KReplacing:
1.00 atm* 150 L= n*0.08206 [tex]\frac{atm*L}{mol*K}[/tex] *273 K
Solving:
[tex]n=\frac{1.00 atm* 150 L}{0.08206 \frac{atm*L}{mol*K}*273 K}[/tex]
n= 6.69 moles
Being Cl= 35.45 g/mole, the molar mass of chlorine gas is:
Cl₂=2*35.45 g/mole= 70.9 g/mole
So if 1 mole has 70.9 grams, 6.69 moles of the gas, how much mass does it have?
[tex]mass=\frac{6.69 moles*70.9 grams}{1 mole}[/tex]
mass= 474.321 grams ≅ 474 grams
474 grams of chlorine gas are present in a 150 liter cylinder of chlorine held at a pressure of 1.00 atm and 0 °C
Lap safety rules crossword
What’s the correct IUPAC name for the compound shown here?
Answer : The correct IUPAC name for the compound is, 2,2,4,5-tetramethyl-3-ethylhexane.
Explanation :
The basic rules for naming of hydrocarbons are :
First select the longest possible carbon chain.
The longest possible carbon chain should include the carbons of double or triple bonds.
The naming of alkane is done by adding the suffix -ane, alkene by adding the suffix -ene, alkyne by adding the suffix -yne.
If two or more similar alkyl groups are present in a compound, the prefixes di-, tri-, tetra- and so on are used to specify the number of times of the alkyl groups in the chain.
In the give compound, the longest possible carbon chain has 6 carbon atoms. So, the prefix used will be 'hex-' and also the carbon has single bond between them, so it is an alkane. Four methyl group is present at 2,2,4,5 position of carbon chain and one ethyl group is present at 3 position.
Hence, the correct IUPAC name for the compound is, 2,2,4,5-tetramethyl-3-ethylhexane.
Tetramethyl-2,2,4,5-ethylhexane is the proper IUPAC name for the substance.
Basic guidelines for hydrocarbon naming are as follows:
Choose the longest carbon chain you can.
The carbons of double or triple bonds should be included in the longest carbon chain possible.
The suffixes -ane, -ene, and -yne are used in the naming of alkane, alkene, and alkyne, respectively.
If a compound has two or more identical alkyl groups, the prefixes di-, tri-, tetra-, and so on are used to indicate how many times the alkyl groups are present in the chain.
The longest feasible carbon chain in the given chemical contains 6 carbon atoms. Since there is only one bond between the carbon atoms, the prefix will be "hex-," and an alkane is what is being described. On the carbon chain, there are four methyl groups at positions 2, 2, 4, and 5, and one ethyl group at position 3. Consequently, 2,2,4,5-tetramethyl-3-ethylhexane is the right IUPAC designation for the substance.
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Light travels at roughly 3.00×108ms. What is this speed in miles per minute? Use 1mi=1609.344m and 60s=1min.
Answer:
1.12x10⁷ mi / min
Explanation:
Speed is a magnitude defined as the distance an object travels per unit of time.
Speed light is 3.00x10⁸ m/s. To convert this to miles per minute we need to convert the meters to miles and the seconds to minutes:
3.00x10⁸ m/s * (1mi / 1609.344m) = 186411.4 mi/s
186411.4 mi/s * (60s / 1min) =
1.12x10⁷ mi / minwhat does control mean in scientific method
Answer:
A scientific control is an experiment or observation designed to minimize the effects of variables other than the independent variable. This increases the reliability of the results, often through a comparison between control measurements and the other measurements.A scientific control is an experiment or observation designed to minimize the effects of variables other than the independent variable. This increases the reliability of the results, often through a comparison between control measurements and the other measurements.
Explanation:
Let's all give it up for GOOGLE! where you can literally get an answer to something.
What are the laws of Newton?
Answer:
an object that is at rest will stay at rest inless a force acts upon it.
An oject that is in motion will not change its velocity unless a force acts upon it.
Answer:
First law
In an inertial frame of reference, an object either remains at rest or continues to move at a constant velocity, unless acted upon by a force.[2][3]
Second law
In an inertial frame of reference, the vector sum of the forces F on an object is equal to the mass m of that object multiplied by the acceleration a of the object: F = ma. (It is assumed here that the mass m is constant – see below.)
Third law
When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.
You found several studies related to the service provided by the company. Which data will you use to make an informed decision? Check all that apply.
data from a celebrity magazine
data verified by other studies
data provided by an ice cream manufacturer
data gathered once to show the reliability of the company
data from a report put out by a government agency
Answer: it’s b,c and e ,your welcome :) (just took the test on edge)
Answer:
B. data verified by other studies
C. data provided by an ice cream manufacturer
E. data from a report put out by a government agency
Explanation:
H
Н
НЕС-С-ОН
1
Hн
Look carefully at the structural drawing for ethanol above.
How many carbons (C) does an ethanol molecule have?
2
3
6
1
HELPPPPPPPP
Answer:c
Explanation: it's easy
Indicate the net charge of lysine at pH 9.5.
Answer:
Explanation:
An amino acid like lysine has both the acidic and basic group . They are amphoteric in nature ie they can react with both acid and base . In acidic or basic medium they carry charge of either positive or negative nature .
Lysine is also an amino acid . It has both acidic and basic group . The pka value of its basic side chain is 10.5 . Hence at pH more than it it is neutral or have no charge but at pH value less than 10.5 , it acquires H⁺ ion and becomes positively charged
Hence at pH value of 9.5 which is less than 10.5 , it will be positively charged . It will have net charge of + 1 .
---- NH₂ + H⁺ = ------ NH₃⁺
A sprinter is running 200.0 m in 21.9s. What is the average speed of the sprinter in km per hour?
Answer:
Average speed = 333.3 km/hrExplanation:
The average speed of a body can be found by using the formula
[tex]Average \: \: speed = \frac{distance}{time} [/tex]
To find the average speed in km/h first convert the distance from m to km and the seconds from s to hr.
For the distance
2000 m
1000 m = 1 km
2000 m = 2000/1000 = 2 km
For the seconds
21.9 s
3600 s = 1 hr
21.9 s = 21.9/3600 = 0.006 hrs
Substitute the values into the above formula and solve for the Average speed
That's
[tex]Average \: \: speed = \frac{2}{0.006} [/tex]
We have the final answer as
Average speed = 333.3 km/hr
Hope this helps you
find how many natural numbers are there between 80 and 120 step by step plz
When neurotransmitter is released into the synaptic cleft, it is taken up by the post-synaptic neuron.
Answer:
Plz make me brainliest
Explanation:
The neurotransmitters released into the cleft diffuse through it to reach the post-synaptic neuron. Neurotransmitters remain in cleft for only some time. They are either taken up by the presynaptic neuron or are broken down by the enzymes present in the synaptic cleft. The post-synaptic neuron contains several receptors on its plasma membrane
Rank the following bonds in order of decreasing bond length, based on periodic trends, starting with the longest bond at the top of the list.H-S H-I H-Se H-BI. H-I II. H-SeIII. H-BrIV. H-S
Answer:
H-BI,H-Se,H-S,H-I,H-Br
Explanation:
One thing that must be kept in mind is that atomic size increases down the group and decreases across the period. The bond lengths of species are influenced by the relative sizes of atoms or ions present in the bond.
The bonds in the answer have been arranged on basis of their decreasing atomic size because the greater the atomic size of the atoms, the greater the bond length and vice versa.
Place these hydrocarbons in order of decreasing boiling point. Rank from highest to lowest boiling point. 1. Paraffin, C40Hg2 2. Propane, G2H53. Hexane, C6H14 4. 2,2-dimethylbutane, C6 H14 5. Heptadecane, C17H36A. Highest BPB. Highest BP
Answer:
Paraffin > Heptadecane > Hexane > 2,2-dimethylbutane > Propane
Explanation:
It must first be establish that all the molecules listed in the question are alkanes. For alkanes, the intermolecular forces between the molecules of alkanes increases with increasing molecular weight. This is as a result of increase in the surface area of the molecule. Increase in surface area implies a greater degree of dispersion forces.
This is the reason why high boiling points are observed for high molecular weight alkanes.
Calculate the degree of unsaturation (or IHD, Index of Hydrogen Deficiency) for C8H12.
Answer:
4.
Explanation:
Hello,
In this case, for the calculation of the degree of unsaturation, we apply the following formula:
[tex]Degree\ of \ insaturation=C-\frac{H}{2}[/tex]
Thus, since we have eight carbon atoms and twelve hydrogen atoms, it turns out:
[tex]Degree\ of \ insaturation=8-\frac{12}{2}=8-6=4[/tex]
It means that four substituents are missing in order saturate the molecule.
Regards.
What are the properties of the aluminum in the
can? Check all that apply.
It conducts electricity well.
It is solid
It is brittle.
It does not react easily with water or air.
It is less dense than water.
Answer:
What are the properties of the aluminum in the can? Check all that apply.
*It conducts electricity well.
*It is solid.
It is brittle.
*It does not react easily with water or air.
It is less dense than water.
Explanation:
a b d
The properties of aluminium (Al) includes electrical conductivity, solid and it does not react easily with water. Therefore, option A, B and D are correct.
What is aluminium?Aluminium is a common metal we use day to day. It is an electropositive element and due to its metallic nature, Al shows electrical and thermal conductivity. Unlike other metals Al can withstand brittleness and it is ductile in nature.
Aluminium easily reacts with oxygen and forms an oxide layer on its surface so that, it can resist attack by other chemical such as acid or bases as well as oil and water. Hence water does not easily react with aluminium.
Therefore, we can say that aluminium is a solid which conduct electricity and not easily reacts with water.
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Yesinia read that certain perfume ingredients, called esters, would agitate bees. Because perfume formulas are secret, she decided to determine whether the unknown Ester X was present in four different perfumes by observing the bees’ behavior. She placed a saucer containing 10 mL of the first perfume 3 meters from the beehive. She recorded the time required for the bees to emerge and made observations on their behavior. After a 30-minute recover period, she tested the second, third and four perfumes. All experiments were conducted on the same day when the weather conditions were similar, that is, air temperature and wind. What was the hypothesis? What would be the control group? What is the experimental group? What was deliberately changed? What responded to the change?
Answer:
Hypothesis: IF the perfumes contained Ester "X", THEN the bees would be agitated
Control group: The control group would be the group of bees that did not receive any perfume treatment
Experimental group: Bees that were exposed to the different perfumes
Independent variable: The type of perfumes
Dependent variable: the behavior of the bees
Explanation:
An hypothesis is a testable explanation or suggested solution to a problem that is subject to testing (for proving or disproving) via experimentation. The hypothesis of this experiment will be: IF the perfumes contained Ester "X", THEN the bees would be agitated
The control group of an experiment is the group that does not receive the experimental treatment or the group whose independent variable is not changed. In this case, there is no stated control group but control group of this particular experiment could be the BEES THAT WERE NOT EXPOSED TO ANY PERFUME.
The experimental group, as opposed to the control group, is the group that receives experimental treatment. In this case, it is the group of bees that were exposed to the different types of perfumes.
In an experiment, the variable that is deliberately changed by the experimenter is called the independent variable. The independent variable in this question is the TYPE OF PERFUME given to the bees.
The variable that responds to the changes made to the independent variable is called the dependent variable. The dependent variable, which is the measured variable, is THE BEHAVIOR OF THE BEES.
VSEPR theory predicts an identical shape for all of the following, except:_______. A. NH_3 B. H_3O^+ C. BH_3 D. CH_3^+ E. All of these choice same geometry.
Answer:
C. BH_3
Explanation:
The VSEPR is known as the valence shell electron pair repulsion theory. The VSEPR theory determines the total number of electron pairs (TEP) surrounding the central atom of a species. The TEP consists of the bond pairs (BP) and lone pairs (LP). In this model, all the electron pairs (like charges) will orient themselves in such a way as to minimize the electrostatic repulsion between them. These repulsions determine the geometry of the covalent bonds around the central atom.
In the options given, all the molecules have identical geometry except BH_3. This is as a result of the absence of a lone pair on the BH_3 compound.
think about an inflated balloon and a small bag of marbles that is half its size . which one has more volume explain
The object with more volume is the inflated balloon
Explanation:
Volume is about how much space an object or material occupies; in this context, if the inflated balloon has the double size of the bag of marbles then the balloon has more volume because this is occupying more space.
Moreover, the volume should not be confused with other factors such as mass or weight because it is likely the marbles weight more but this does not imply the marbles have more volume. Also, the balloon contains gas and gases tend to expand and occupy more space, which does not occur with solids such as marbles because these have a defined volume.
We can see each other in the classroom right now because we
a.reflect visible light
b. absorb visible light
c.reflect infrared light
d.absorb radio waves.
Answer:
The answer is A
Reflect visible light
Calculate the solubility of PbCO3 in water at 25 degree C.
Answer:
2.7 × 10⁻⁷ M
Explanation:
Step 1: Write the reaction for the solution of PbCO₃
PbCO₃(s) ⇄ Pb²⁺(aq) + CO₃²⁻(aq)
Step 2: Make an ICE chart
To relate the solubility of PbCO₃ (S) with its solubility product constant (Ksp) we will make an ICE chart.
PbCO₃(s) ⇄ Pb²⁺(aq) + CO₃²⁻(aq)
I 0 0
C +S +S
E S S
The solubility product constant is:
Ksp = 7.4 × 10⁻¹⁴ = [Pb²⁺] × [CO₃²⁻] = S²
S = √7.4 × 10⁻¹⁴ = 2.7 × 10⁻⁷ M